I have tried multiple things to sort out the issue but to no avail.

BHPian greenhorn recently shared this with other enthusiasts.

Hi all,

I'm facing this rather weird issue. My recent aftermarket parking sensor has started to act up randomly - mostly when the engine is running and at idle RPM.

I'll let my FNG sort it out, but figured I'll pick your brains too.

Steps tried so far

• Replaced with a brand new parking unit, still happening.
• Replaced the reverse switch in the gearbox which provides the signal for the reverse light that's powering the sensor.
• One thing we were able to spot was that the issue goes away when I rev the engine.
• I'm using uprated T15 LED bulbs in the reverse light, but this sensor was working for several months without issues with the same bulb.
• My theory is that the voltage regulator on the alternator is falling. Going by past history, my alternator is due for an overhaul anyway (lasts 3-4 years between overhauls) plus at low rpm tachometer keeps dying.

You can see the voltages in the video. They look low to me. But the weird thing is that the sensor works fine at 11.6v with the engine off, but goes kaput at 12.5 with the engine on. I'm getting a lot of flickering at idle too with my bulbs.

Worst case I'll just put in a direct line from the battery with a relay triggered by the reverse light signal, but what's wrong really?

I'm planning to take a multimeter and check the voltages at the sensor.

Here's what BHPian audioholic had to say about the matter:

Install the sensors in another car and check. I think might be something to do with ultrasonic interference from some component in the car or the ECM. Checking the voltage at the sensor won't reveal anything since the sensor will be driven at its own voltage and not necessarily 12v. You would do better with an oscilloscope to check the reflections on the sensor if you really want to debug the sensor. Since you say the issue goes away when you rev the engine, I really think it's the injectors which are driven by a frequency that causes interference on your reverse sensor.

Here's what BHPian Jeroen had to say about the matter:

Check all the wires for chaffing. Strange problems such as these are often caused due to poor grounding/mass. So check and clean all grounds, connectors and so on.

Here's what BHPian CannedShroud had to say about the matter:

When the car's engine turns on, it switches from a 12v system to a 14v system. Not exactly... But if you check the voltage through the OBD port, you'll find the same findings. Maybe the step-down driver on your cam has fried?

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Have tapped the wire from the dome lights and it glows whenever the door the opened, irrespective of the dome light switch position.

BHPian Blow Horn Ok recently shared this with other enthusiasts.

Recently added the MGA branded footwell lights to my 2017 Aspire. Have tapped the wire from the dome lights and it glows whenever the door the opened, irrespective of the dome light switch position. A nice and warm feature to have. Ironically I have also installed MGA branded reverse parking sensors and they are flawless since 3 years of installation.

Here's what BHPian VWAllstar had to say on the matter:

Looks good. I got one from Ford during delivery. It is managed by an App which connects via BT. It costed me Rs.5000 and used it for max 1 week. After looking at this post, I realized that I have a similar one in my Figo. What you did by connecting to an action (opening of door) makes it more usable and desirable now.

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The Ministry of Road Transport and Highways has issued a notification mandating reverse parking alert systems for trucks and buses manufactured from April 2020.

The government has said that all trucks and buses will be required to have rear sensors that sound a warning when an object is at a certain distance from the vehicle. The alert system could also include reverse cameras. Tractors including puller tractor for semi-trailers, trailers and modular hydraulic trailers will be exempted from this rule. 

From July 2019, reverse parking sensors will also be mandatory for cars and other 4-wheelers.

Source: Economic Times

Rear parking sensors or rear view cameras will soon be made compulsory for all new cars sold in the country. This announcement was made by Mr. Abhay Damle, Joint Secretary, Ministry of Road Transport and Highways. The step is being taken to control the increasing number of cases of small children and pedestrians getting injured due to reversing vehicles.

According to the Government, studies have revealed that though the IRVM and ORVMs give an idea about the vehicles behind one's car, smaller obstacles as well as children are often not visible through these mirrors. The presence of reverse parking sensors can alert the driver of a hindrance while reversing, thus avoiding any accidents that may occur due to blind spots at the rear.

The Ministry of Road Transport and Highways (MoRTH) is expected to issue a notification directing all manufacturers to offer reverse parking sensors as standard on all cars, even in the base models. No specific time window has yet been announced for implementing this new rule.

The Government is also planning to make speed warning systems compulsory on all cars. This is being done to curb what is believed to be the biggest cause of accidents - over-speeding.